1. Field of the Invention
The present invention relates to a radiation-type diagnosis apparatus wherein a storage phosphor sheet is used as a medium for receiving the radiation passing through a region within a subject and recording the image of this region, along with a bar code identifying the sheet, and more particularly to a diagnosis apparatus wherein image data is prevented automatically from being read from a storage phosphor sheet when the sheet takes any position other than a desired one within the apparatus.
2. Description of the Related Art
The storage phosphor sheet is generally known as "imaging plate". The imaging plate is made of a phosphor which absorbs part of the energy of the radiation applied to it, such as X rays, .alpha. rays, .beta. rays, or .gamma. rays. When the imaging plate is scanned with excitation light such as visible light, the plate releases the energy in the form of light.
A method has been proposed and practically used, in which the radiation passing through a region of interest (hereinafter referred to as ROI) of a patient or other subject is applied to the imaging plate. The plate absorbs part of the energy of the radiation, thereby recording the image of this ROI. Whenever required, the imaging plate is scanned with an excitation light beam. As a result, the plate releases the energy in the form of light. A photoelectric device converts this light into image data. A data-processing apparatus process the image data, thus reproducing the image of the ROI. The reproduced image is either printed on a sheet of paper, or displayed by a CRT display.
In the above method of recording and reproducing the image of a ROI of interest, the imaging plate can be repeatedly used, about 1,000 times. The plate is, therefore, an economical recording medium. Actually, the imaging plate is used in various types of radiation-type diagnosis apparatuses.
One of these diagnosis apparatuses is cassette-less X-ray photography apparatus 202 shown in FIG. 1. Also shown in FIG. 1 is image-reading apparatus 200. Image-reading apparatus 200 has a storage section storing a number of imaging plates 201 which are not unrecorded. Bar codes are printed or labeled on the back of each plate 201. The bar code represents the ID number of the imaging plate, and also the conditions under which the image of a ROI should be photographed. One of plates 201 is pulled out from the storage section and inserted into cassette-less X-ray photography apparatus 202. Then, X-ray photography apparatus 202 is operated, thereby recording the image of a ROI of a patient on imaging plate 201. Apparatus 202 reads the data representing the image from plate 201, and also data items representing the ID number and the photographing conditions from the bar code, and transfers the image data and also the data items to image-reading apparatus 200 through a data transfer line (not shown). As is illustrated in FIG. 2, imaging plate 202 is removed from X-ray photography apparatus 202 and stored in the storage section of image-reading apparatus 200.
X-ray photography apparatus 202 performs the same image-recording/reproducing operation on the other imaging plates 201 supplied from image-reading apparatus 200 and inserted into it, one after another. These plates 201 are also stored in the storage section of apparatus 200.
When required, image-reading apparatus 200 is operated, thereby reading the image data from any one of imaging plates 201. Apparatus 200 also reads the ID number and the photographing conditions from the bar code printed or labeled on the back of the plate. The ID number, thus read, will be used as reference data in reading the image data from plate 201 over again, and the photography conditions, thus read, will be used in examining the image of the ROI to make an accurate diagnosis. The data items showing the ID number and the photography condition are supplied to an external data-processing system (not shown), together with the image data.
Each imaging plate 201, which has bar codes printed or labeled on its back, is usually a flat square plate. Hence, there is the possibility that plate 201 is positioned erroneously within X-ray photography apparatus 202 or within image-reading apparatus 200. When plate 210 is positioned erroneously in apparatus 202, the ID number cannot be read from the bar code, and the image recorded on plate 201 cannot be identified. When it is erroneously positioned in image-reading apparatus 200, neither the ID number nor the photography conditions can be read from bar code. Consequently, the image of the ROI, even if reproduced from plate 201, cannot be identified, and the conditions, under which the ROI has been photographed, cannot be ascertained. As a result of this, the ROI cannot be diagnosed a accurately.
More specifically, if unrecorded imaging plate 201 is appropriately placed in tray 300 as is shown in FIG. 3, with two bar codes 302A and 302B positioned correctly, the ID number of plate 201 will be read from either bar code when tray 300 is inserted into X-ray photography apparatus 202 or into image-reading apparatus 200. However, if plate 201 is erroneously placed in tray 300, the ID number can not be read from bar code 302A o 302B. The image of the ROI cannot be identified. Neither can be conditions, under which the ROI has been photographed, be ascertained. As a result, the ROI cannot be diagnosed accurately.